Functional and immunohistological studies on cancer-associated carbonic anhydrase IX

Abstract The carbonic anhydrases (CAs) catalyze the reversible hydration of carbon dioxide. In mammals, there are 13 active isoenzymes, which clearly differ in their cell localisation, tissue distributions and functions. CA IX, a unique transmembrane member of the CA gene family, is a tumour-associated protein which is thought to be involved in malignant cell invasion, adhesion and the regulation of cell proliferation. The main focus in the present study was on elucidating the function and expression of CA IX in normal and malignant tissues, especially in the alimentary tract. The functional studies also included CA II, which is regarded as another important CA isoenzyme in the alimentary tract. CA IX immunostaining showed a decrease in the staining intensity of gastric adenomas with increasing dysplasia grade. Well differentiated carcinomas of the intestinal type showed expression comparable to that in the normal mucosa, while expression was decreased in the less differentiated tumours. CA IX deficiency (Car9-/-) genotype and C57/BL6 strain were the main factors which increased the susceptibility of CA IX deficient mice fed on either a normal or high-salt diet to histological abnormalities, including foveolar hyperplasia and glandular atrophy in the gastric body mucosa, while CA II deficiency was associated with only minor histological abnormalities. In a physiological analysis, CA IX played only a minor role in duodenal bicarbonate secretion (DBS), whereas absence of CA II in mice completely abolished the stimulatory effect of E-type prostaglandin 2 (PGE2) on duodenal alkalisation. The results demonstrate that CA IX expression is diminished in most gastric tumours. The variations observed in its expression support the concept that gastric adenomas and carcinomas do not emerge as progressive steps on a single pathway but may instead represent distinct entities with heterogenic genetic backgrounds. In the stomach, CA IX is mainly involved in the regulation of tissue morphogenesis in the body mucosa, while CA II has a major role in maintaining the gastroduodenal acid/base balance

Estimating prevalence of anxiety and mood disorder in survey data using the GHQ12: Exploration of threshold values

Background and Objectives: Our study explored the validity of different threshold values on the 12-item version of the General Health Questionnaire (GHQ12) for estimating the prevalence of anxiety and mood disorders (AMD) in Ontario population survey data. Methods: Data were drawn from the 2003, 2004 and 2006 cycles of the CAMH Monitor (N = 7,126), an ongoing general population survey of Ontario adults aged 18 and older, which includes the GHQ12. The concordance of different threshold values on the GHQ12 for determination of AMD with a criterion based on individuals who were prescribed either anti-anxiety or anti-depressant drugs in the past 12 months and who reported 14 or more mentally unhealthy days in the past 30 days was examined using receiver operator characteristic (ROC) analysis. Results: Concordance between the GHQ12 determination of AMD and the criterion measure reached “moderate” levels. ROC analysis revealed an area under the curve (AUC) of 0.89. At a GHQ12 threshold value of 4, the specificity and sensitivity values obtained were 0.92 and 0.71, respectively. Also at that value, the estimated prevalence of AMD was nearly identical to that seen in recent Canadian studies using the CIDI. Conclusions: These analyses suggest that the GHQ12 may be suitable for providing a proxy measure of AMD for epidemiological and surveillance purposes. A threshold score of 4 seems to be most suitable for these purposes when using Canadian data

Carbonic anhydrase isozyme-II-deficient mice lack the duodenal bicarbonate secretory response to prostaglandin E(2)

Duodenal bicarbonate secretion (DBS) is accepted as the primary mucosal defense against acid discharged from the stomach and is impaired in patients with duodenal ulcer disease. The secretory response to luminal acid is the main physiological stimulus for DBS and involves mediation by PGE(2) produced by mucosal cells. The aim of this investigation is to elucidate the role of carbonic anhydrases (CAs) II and IX in PGE(2)-mediated bicarbonate secretion in the murine duodenum. CA II- and IX-deficient mice and different combinations of their heterozygous and WT counterparts were studied. A 10-mm segment of the proximal duodenum with intact blood supply was isolated, and DBS was titrated by pH-stat (TitroLine-easy, Schott, Mainz, Germany). Mean arterial blood pressure (MAP) was continuously recorded, and blood acid/base balance and gastrointestinal morphology were analyzed. The duodenal segment spontaneously secreted HCO(3)(-) at a steady basal rate of 5.3 ± 0.6 μmol·cm(-1)·h(-1). Perfusing the duodenal lumen for 20 min with 47 μM PGE(2) caused a significant increase in DBS to 13.0 ± 2.9 μmol·cm(-1)·h(-1), P < 0.0001. The DBS response to PGE(2) was completely absent in Car2(-/-) mice, whereas basal DBS was normal. The CA IX-deficient mice with normal Car2 alleles showed a slight increase in DBS. Histological abnormalities were observed in the gastroduodenal epithelium in both CA II- and IX-deficient mice. Our data demonstrate a gastrointestinal phenotypic abnormality associated with CA II deficiency. The results show that the stimulatory effect of the duodenal secretagogue PGE(2) completely depends on CA II

Monoclonal antibodies raised against 167–180 aa sequence of human carbonic anhydrase XII inhibit its enzymatic activity

Abstract Human carbonic anhydrase XII (CA XII) is a single-pass transmembrane protein with an extracellular catalytic domain. This enzyme is being recognized as a potential biomarker for different tumours. The current study was aimed to generate monoclonal antibodies (MAbs) neutralizing the enzymatic activity of CA XII. Bioinformatics analysis of CA XII structure revealed surface-exposed sequences located in a proximity of its catalytic centre. Two MAbs against the selected antigenic peptide spanning 167-180 aa sequence of CA XII were generated. The MAbs were reactive with recombinant catalytic domain of CA XII expressed either in E. coli or mammalian cells. Inhibitory activity of the MAbs was demonstrated by a stopped flow CO2 hydration assay. The study provides new data on the surface-exposed linear CA XII epitope that may serve as a target for inhibitory antibodies with a potential immunotherapeutic application